The art of otoscopes has been contributed to by a number of devices periodically proposed with the advancement of medical diagnostic devices. In recent years, video technology has been adapted for use with such diagnostic devices. Early attempts at providing video capability to otoscopes involved the use of a video adaptor and beam splitter which were mounted onto a conventional hand-held otoscope. This type of adaptor is illustrated in U.S. Pat. No. 5,239,984, issued to R. M. Cane et al. and entitled: "Hand-Held Opto-Diagnostic Instrument System". While providing an advancement to the art, the Cane et al. device is limited in that it relies on a beam splitter to divide light reflected from the object under investigation. Therefore, about one half of the illumination is directed to the eyepiece of the scope and is therefore lost. This type of attachment system also relies on being used with a standard otoscope or ophthalmoscope requiring a relatively large battery source for illumination.
More recently proposed video otoscopes include the type disclosed in U.S. Pat. No. 5,363,839 to J. D. Lankford. The Lankford device includes an otoscope head connected to a hand-holdable body portion. The imager or video camera of this device is positioned at the proximal end of the body portion. An elongated rod lens is employed to communicate light information from the distal tip of the device to the relatively distant proximally located video camera. Rod lenses, as currently known, are extremely expensive and fragile and are subject to breakage upon impact which might be ordinarily expected during use of this kind of device.
Certain endoscopes disclose positioning the CCD or other solid-state imager in the distal head. Examples include U.S. Pat. Nos. 4,639,772 to Sluyter, et al, 4,918,521 to Yabe, et al, 5,050,584 to Matsuura, and 5,379,756 to Pileski, et al. Each of the above patents describe optimal placement of the imager relative to a viewing optical system which focuses an optical image of the target onto the substrate of the imager. An illumination optical system projects light onto the target to allow viewing by the video camera through the viewing optical system. The illumination optical system, includes a bundle of optical fibers which are either disposed in a circumferential ring around the imager and viewing optical system as described in the '756 patent, or retained in a bundle and disposed parallel to the viewing optical system as described in the '521 patent to Yabe, et al.
Otoscopic examination is generally more unique than other endoscopic applications, however, for at least two reasons. First, the tympanic membrane is relatively large (approximately 6-7 mm for an average adult) as compared to the auditory canal (averaging about 4-5 mm). It is therefore desired to obtain as large a field of view as possible to effectively perform an examination. This was not previously achieved with so-called traditional optical otoscopes, as shown in FIG. 1. Use of a Hopkins or other rod lens assembly, however, provided a greater field of view, allowing the entirety of the tympanic membrane to be viewed all at once as shown in FIG. 2. With the advent of video otoscopes, such as described in the Lankford patent, it is still desired that a maximized field of view be achieved to allow the entire membrane to be viewed at once. It is also desired to attempt to replace the rod lens assembly, due to its inherent fragility and high cost.
Second, it is also highly desirable in otoscopic examinations to pressurize or apply a vacuum within the ear canal to stimulate the tympanic membrane, a feature commonly referred to as insufflation. Though contemplated in the Lankford patent, the otoscope described therein utilizes a proximally positioned electronic imaging element, which does not have the spatial constraint problems affecting an otoscope having a distally arranged image sensor, viewing optical system and illuminating optical system, respectively.
Therefore, there is a need to provide insufflation capability to a video otoscope having a CCD or other similar imager distally arranged within the insertion portion of the instrument to provide an enhanced field of view without use of a rod lens assembly, and done in a compact manner so as not to interfere with the illuminating or viewing optical systems.